Vitamins and Calcium Supplements (cont.)

Betty Kovacs, MS, RD

Betty is a Registered Dietitian who earned her B.S. degree in Food and Nutrition from Marymount College of Fordham University and her M.S. degree in Clinical Nutrition from New York University. She is the Co-Director and Director of nutrition for the New York Obesity Research Center Weight Loss Program.

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

Vitamin A

What is it, and what does it do?

Vitamin A is a fat-soluble vitamin that is broken down into two categories: preformed vitamin A comes from animal foods, and provitamin A carotenoid comes from plant foods.

Vitamin A serves many functions:

helps regulate the immune system to prevent and fight infections

helps form and maintain healthy teeth, skin, and tissues

produces the pigments in the retina of the eye

promotes good vision

How much do I need to consume?

The Recommended Dietary Allowances (RDA) for vitamin A are listed as International Units (IU) of Retinol Activity Equivalents (RAE). This is done to account for the different actions of both forms of vitamin A.

RDA for vitamin A:

Age

Males

Females

Pregnancy

Lactation

1 to 3 yrs

1,000 IU

1,000 IU

N/A

N/A

4 to 8 yrs

1,320 IU

1,320 IU

N/A

N/A

9 to 13 yrs

2,000 IU

2,000 IU

N/A

N/A

14 to 18 yrs

3,000 IU

2,310 IU

2,500 IU

4,000 IU

19+

3,000 IU

2,310 IU

2,565 IU

4,300 IU

There is insufficient information to establish an RDA for vitamin A for infants. In this case, an Adequate Intake (AI) has been established:

Age

Males and Females

0 to 6 months

1,320 IU

7 to 12 months

1,650 IU

What are sources of vitamin A?

Vitamin A can be found in animal and plant foods. The animal food sources are better absorbed and used by the body than the plant sources. There are also many foods that are fortified and enriched with vitamin A.

The content of vitamin A in animal and plant foods (from beta-carotene):

Food

Amount

Vitamin A

Apricot nectar, canned

½ cup

1,651 IU

Cantaloupe

1 cup cube

5,411 IU

Carrot juice, canned

½ cup

22,567 IU

Carrots, boiled

½ cup slices

13,418 IU

Carrots, raw

1 - 7 ½ inches

8,666 IU

Cheese, cheddar

1 oz

249 IU

Kale, frozen, boiled

½ cup

9,558 IU

Liver, beef, cooked

3 oz

27,185 IU

Liver, chicken, cooked

3 oz

12,325 IU

Milk, fortified skim

1 cup

500 IU

Oatmeal, instant, fortified

1 cup

1,252 IU

Papaya

1 cup cubed

1,532 IU

Peach

1 medium

319 IU

Peas, frozen, boiled

½ cup

1,050 IU

Pepper, red, raw

1 ring

313 IU

Spinach, frozen, boiled

½ cup

11,458 IU

Spinach, raw

1 cup

2,813 IU

Vegetable soup, canned

1 cup

5,820 IU

Do I need to take a vitamin A supplement?

Vitamin A is stored in the liver, so there is a supply that can be used during short-term periods when intake is not adequate to meet your needs. People with medical conditions that interfere with the absorption of vitamin A may need to take a supplement. These conditions include celiac disease, Crohn's disease, inflammatory bowel disease, and pancreatic disorders. Because vitamin A can be toxic at high levels, it's best to discuss supplements with your physician.

What happens if I don't have enough vitamin A?

Early vitamin A deficiency leads to impaired night vision, and advanced vitamin A deficiency can lead to corneal ulcers, xerophthalamia (dry eye), scarring, night blindness or total blindness. In developing countries, vitamin A deficiency is an important cause of blindness among children. Children with vitamin A deficiency are also more likely to develop diarrhea and respiratory infections than children who are not vitamin A deficient. Vitamin A deficiency is rare among healthy adults in the United States.

Vitamin A deficiency can also be a problem for people with Crohn's disease, celiac disease, pancreatic disorders, and people who do not consume animal foods.

Is there such a thing as too much vitamin A?

When excess amounts of vitamin A are being stored in your body, the condition is called hypervitaminosis A. The harmful effects of hypervitaminosis A are birth defects, reduced bone density that may result in osteoporosis, central nervous system disorders, and liver abnormalities.

Acute vitamin A toxicity may result from consuming very large quantities of vitamin A over a short period of time. The symptoms are nausea, vomiting, irritability, drowsiness, altered mental status, anorexia, abdominal pain, blurred vision, muscle pain with weakness, and/or headache. Elderly people and people who drink alcohol heavily are more susceptible to vitamin A toxicity.

The Institute of Medicine states that "beta-carotene supplements are not advisable for the general population," although they also state that this advice "does not pertain to the possible use of supplemental beta-carotene as a provitamin A source for the prevention of vitamin A deficiency in populations with inadequate vitamin A."

The Tolerable Upper Limit (UL) for vitamin A is:

Age

Males and Females

Pregnancy

Lactation

0 to 1 year

2,000 IU

N/A

N/A

1 to 3 years

2,000 IU

N/A

N/A

4 to 8 years

3,000 IU

N/A

N/A

9 to 13 years

5,610 IU

N/A

N/A

14 to 18 years

9,240 IU

9,240 IU

9,240 IU

19+ years

10,000 IU

10,000 IU

10,000 IU

In the ATBC trial, subjects given beta-carotene had a higher incidence of lung cancer than subjects not given beta-carotene. The Institute of Medicine did not set ULs for carotene or carotenoids. However, the recommendation is that beta-carotene supplements are not advisable for the general population.